Multi-protocol label switching (MPLS)-based virtual lease lines (VLL) and other transparent tunneling mechanisms (e.g., TLS) have been provided. In some implementations, Martini encapsulation is used to tunnel customer Ethernet frames between customer sites, through an MPLS provider backbone, in a manner that is largely transparent to the customer, in the sense that hosts at two or more sites appear to one another to be connected to and accessible via a local area network. Typically, MPLS tunnels known as label switched paths (LSP) are used. A VLL (sometimes referred to herein as a “pseudo-wire”) is provided in some cases by establishing a unidirectional virtual circuit in each direction between customer sites. An LSP may be configured to carry traffic associated with multiple virtual circuits. Payload data, such as customer Ethernet frames, is encapsulated in part by adding to the payload an MPLS label stack that includes an LSP tunnel label to be used to transport the payload through the MPLS backbone and a VC label to be used at the far end, e.g., by a far end provider edge router, to associate the payload with an outbound port or other interface.
It is desirable to provide IP connectivity to a remote Ethernet host/router without requiring IP inter-working, i.e., without requiring that routing decisions be made at the far end, e.g., at the far end provider edge router (e.g., ARP cache or routing table). To achieve this goal, any routing decisions must be made at the ingress (near) end. To provide IP connectivity to a remote Ethernet host/router without requiring IP inter-working, therefore, it is necessary to make at the near end any routing decisions necessary to form the Ethernet (or other Layer 2) header that will be required at the far end to reach, without making an IP routing decision at that far end, the IP routing next hop for the payload (e.g., IP packet). Typical prior art routers require a two step process (e.g., one to derive next hop for remote host Ethernet encapsulation and the other to determine the next hop to reach the pseudo-wire) with an external network communication between the two steps. In one approach, a sending host sends an IP packet intended for a far end destination to a router, which adds the IP routing next hop information. The router sends the packet via a network interface to a separate provider edge router that adds the intermediate next hop (LSP/VC) header information and sends the packet via an interface to the LSP. In another approach, the functions of the router and provider edge router described above are integrated into a single physical system, but a separate external network communication between the separate routing processes running in the same physical system is required to perform all of the routing required to forward the packet via the pseudo-wire and have it arrive at the other end with all of the information required to route it to its destination (which may be the ultimate destination or an intermediary like a bridge or router).
Therefore, a way is needed to provide IP connectivity to a remote Ethernet host/router across an Ethernet pseudo-wire without requiring IP inter-working on the far end device and in a in a single forwarding stage while allowing the pseudo-wire to dynamically converge its immediate next hop.